Previously known from U.S. Published Patent Application No. B382,290 is a medium actuated clutch where the rotation-transmitting clutch disc and a mobile pressure plate are in a chamber containing the medium. The chamber is divided into many sub-chambers by the disc and the plate and by means of pressure variations, the pressure plate can be put into motion and the disc and plate surfaces in abutment against each other to carry out clutching.
Such a clutch is applicable to cars with automatic transmission with the clutch thereby in the gearbox. In the gearbox there is oil to operate the clutch and possible oil leakage is of no harm if the leaking oil is flowing directly back into the gearbox. However, a clutch of this kind is not very well fitted for general cases, for instance as a common shaft clutch and, of course, not as a dry clutch in vehicles.